* {
    margin: 0;
    padding: 0;
}

html, body, #app {
    width: 100%;
    height: 100%;
}
/* 版心 */
#main {
    width: 100%;
    height: 100%;
    max-width: 750px;
    min-width: 320px;
    margin: 0 auto;
}

ul, ol {
    list-style: none;
}

a {
    text-decoration: none;
}

img {
    display: block;
}